Goats on the Roof: anchoring an attraction

WORD Rock Drills equipment being used to anchor the coaster's supports at Goats on the Roof.

As the foundation of an alpine coaster shifts, Ross searches for a way to stabilize it.

Goats on the Roof is a tourist attraction in Pigeon Forge, Tennessee—a popular vacation destination—that features live goats grazing its roof and property.

According to the company, the concept of having live goats on a roof dates back 40 years to Al Johnson’s Swedish Restaurant in Door County, Wisconsin. The Johnson family began letting goats graze on the sodded roof of their Sister Bay eatery to attract crowds.

Goats on the Roof in Tennessee features a two-level gift shop that sells a variety of things including branded merchandise, ice cream and fudge.

The biggest attraction—besides the goats—is the alpine coaster. Guests can take a seven minute ride on a 1.5 km track at speeds of almost 50 km/h.

Butting heads with the mountain

Approximately 5 years ago, the owner, Ross, began to see signs of movement in the foundation of his mountain coaster. After further exploration of the issue, Ross discovered that the unique mixture of soil types on the face of the mountain was retaining large amounts of water, which was causing the movement he had noticed.

Due to the challenging soil conditions—2 ft of clay with a shale layer and overburden—his first attempts to stabilize the mountain were unsuccessful. The initial contractor had attempted various methods of soil nailing but they were unsuccessful. The movement of the mountain broke the soil nails.

Under the clay layer, there is rock suited for proper anchorage of the Goats on the Roof Alpine mountain coaster supports.

Goats in front of the Alpine Coaster at  Goats on the Roof in Tennessee.

What’s the WORD?

Having already purchased an 18 ton excavator for other areas of his work, Ross decided to research what it would take to solve this project himself. After some time, Ross came across WORD Rock Drills.

Upon reaching out to WORD, the company’s salesman, John, gathered information from Ross and other contacts within the industry to work toward finding a solution.

WORD Rock Drills equipment being used to anchor the coaster's supports at Goats on the Roof.

Through WORD, Ross was put in contact with Billy Smith, a driller in his area that had previously worked with attachment machines and would have the knowledge and experience to help him reach the best solution.

After consulting Billy, Ross purchased a WORD EX125 excavator attachment with a second DF560 drilling head.

This specific configuration of excavator attachment featured a 24 ft drilling feed, radio remote control system, dual rotation for increased maneuverability, and a clamp and breaker.

The M125 drilling head that was shipped pre-installed on the machine is a hydraulic drilling head with up to 14,000 ft/lbs of rotation torque and the capability to handle up to a 13” hole.

According to WORD Rock Drills, the second motor sent, the DF560, is ideal for smaller grouted holes. It has 863-1438 ft/lbs rotation torque, 175 bar max rotation pressure, and up to 250 rpm.

A unique feature of the WORD Rock Drill attachment is the quick change motor mount design.

This design feature allows operators to change between two types of motors without purchasing a new machine. So, Ross is able to change between the M125 and DF560 for his project, without having to purchase another machine entirely.

As this project continues, Ross has been using the WORD Rock Drills equipment to install anchors as close to the base of the coaster as possible. The drill uses air to flush the hole of the trapped underground water that initially caused the coaster’s movement and subsequently thwarted the attempt at soil nailing.

Also, after anchor installation, a footing is being installed and tied with a single pile cap that will connect all of the anchors and bind them together.

Depending on the specific location, vertical anchors are drilled from 65-105ft with the goal of having at least a 15 ft grouted anchor at each location.

Additionally, because the drill has to be so close to the mountain coaster, drilling has to be done in short intervals. The ride shuts down for 10-15 minutes so that the crew can drill and then opened for riders to move through the area. To keep the coaster in operation, this cycle will be repeated until all of the drilling is done.